Archery bow with force-multiplying linkage

ABSTRACT

An archer&#39;&#39;s bow utilizing a pair of end mounted rotatable rocker arm members to develop a mechanical advantage permitting the use of less force to hold the bow in a fully drawn position than would be required without such members. The bow comprises a bow member, end mounted rotatable rocker arm members, a draw cable member or bowstring connecting the rocker arms, an elastic device resisting rotation of the rocker arms, and link means to ensure substantially equal but opposite angular displacement of the rocker arms.

2,307,021 1/1943 Cordrey ct al. i

O United States Patent m1 3,595,213

[72] Inventor Willis A.Storer 3,486,495 12/1969 Allen 124/24 720 N.Federal Ave.. Mason City, Iowa 1.457.983 6/1923 Malone 124/24 $0401 rPrimary Exammer Richard C. Pinkham [21] APPLNOV 815342 I AssistantE.raminerWilliam R. Browne F'led 1969 Arrome 'Watson Cole Grindle &Watson 451 Patented July 27, 1971 [54] ARCHERY BOW WITHFORCE-MULTIPLYING LINKAGE 8 Claims, 6 Drawing Figs.

r v ABSTRACT: An archer's bow utllizing a pair of end mounted [52]U.S.Cl 124/23, ble r cker arm members to develop a mechanical ad- 124/30A vantage permitting the use of less force to hold the bow in a [51]Int.Cl F411) 5/00 m drawn position than would be required without such[50] Field of Search l24/23,24, members The bow comprises a bow member,end mounted 2 rotatable rocker arm members, a draw cable member orbowstrin connecting the rocker arms, an elastic device resist- [56]defences cued ing rotati on' of the rocker arms, and link means toensure sub- UNITED STATES PATENTS stantially equal but opposite angulardisplacement of the .124/23 rocker arms.

PATENTEBJULZ'IBH 3,595,213

SHEET 1 BF 2 ovum/me Afro/avers PATENTED JUL2 7 l9?! SHEEIZUFZ ARCHERYBOW WITH FORCE-MULTIPLYING LINKAGE This invention pertains to anarcher's bow. In particular this invention pertains to an archers bowutilizing end mounted rotatable mechanical means to develop a mechanicaladvantage permitting the use of considerably less force for drawing thebow toward and holding it in a fully drawn or loaded position than wouldbe required without such means.

A problem of archers throughout the ages has been to develop a powerfulbow which could be easily handled without fatigue, which could be heldsteady for taking aim, and which could propel an arrow a great distancewith great accuracy. One solution has been the well-known crossbow whichcan be drawn or loaded mechanically, locked into a drawn position bymeans of a solid brace between bow and string, held steady for takingaim, and fired by means of a simple trigger. Loading a crossbow is oftenan awkward task, and the bow itselfis often heavy and cumbersome.

A further problem faced by archers has been the provision of an arrow ofsufficient strength not to snap or splinter at the instant that the fullthrust of the bowstring was loosed against it. The solution in the pasthas generally been to provide a sturdier and therefore heavier arrow.This required a sacrifice of some of the distance across which the fixedstrength bow was capable of driving the arrow. A lighter arrow willgenerally travel faster and farther than a heavier arrow shot from thesame bow.

The aforementioned and other problems have been solved by applicant whohas invented a novel archers bow provided with a pair of rotatablerocker arm members secured to opposite ends of the bow and to thebowstring to generatea mechanical advantage permitting the use of lessforce for drawing the bow toward and holding it in a drawn or loadedposition than would be required without such members. The arrangement issuch that the mechanical advantage increases continuously from a minimumto a maximum as the bow is drawn. As the bowstring is released, thethrust on the arrow builds from a minimum to a maximum, thus permittingthe use of lighter weight arrows than with conventional bows.

The rocker arm members each have first, second and third locationsspaced predetermined distances from each other. These members arerotatably mounted to opposite ends of the bow at their respective firstlocations. The bowstring or draw cable connects the members at theirrespective second locations, while an elastic device applies a force tothe respective third locations tending to resist rotation or angulardisplacement of the pair of rocker arms. A link means assures that theangular displacements of the rocker arms with respect to one another aresubstantially equal in magnitude but opposite in direction. This in turnassures that only an even forward thrusting motion is given to thebowstring and to any arrow it carries, when the bowstring is released.

For a more detailed description, reference is now had to the drawings inwhich:

FIG. 1 is a top plan view of one of the embodiments of the archer's bowof this invention;

FIG. 2 is a side view of the bow of FIG. 1;

FIG. 3 is a bottom plan view of the bow of FIG. 1 shown in a drawncondition;

FIG. 4 is a top plan view of a second embodiment of the archers bow ofthis invention;

FIG. 5 is a top plan view similar to that of FIG. 4 showing a bow of thesecond embodiment in a drawn position; and

FIG. 6 is an incomplete exaggerated front view of parts of the bow androcker arm structure located at the top of the embodiment of thisinvention shown in FIGS. 4 and 5, and illustrates a suggestedimprovement.

A first embodiment 10 of the archer's bow of this invention is shown inFIG. 1 to comprise an elongated bow member 12 having opposite ends 14and 16, a pair of rocker arm members 18, and20, a flexible draw cablemember or bowstring 22, an elastic device 24, and link means 26.

Rocker arms 18 and 20 are each provided with first, second and thirdlocations 28, 30, 32 and 34, 36, 38, respectively, said locations beingspaced predetermined distances from each other. The rocker arms 18 and20 are each rotatably mounted at their respective first locations 28 and34 to opposite ends 14 and 16 of elongated bow member 12. Flexible drawcable member 22 connects at its opposite ends the rocker arm members attheir respective second locations 30 and 36.

The positions of rocker arms 18 and 20 in FIG. 1 havebeen chosen tosimplify the illustration by reducing to a minimum the number of cablesoverlying one another. It is preferable that an actual embodiment of thebow of FIG. I be designed so that in its unloaded rest condition therocker arms are positioned so that second location 30, first location28, first location 34 and second location 36 all lie substantially alongthe same straight line in the order just stated.

The elastic device 24 is connected to the rocker arm members at theirrespective third locations 32 and 38. Device 24 applies to said thirdlocations a force which under normal conditions resists the rotation. orangular displacement of the rocker arms 18 and 20 and urges them toreturn to their original rest or equilibrium position. Device 24 isshown to comprise cable portions 40, 42 and 44, an elastic band 46, anda turn buckle 48 for adjusting the cable lengths. The elastic band 46could be replaced by a metallic coil spring or by other elasticapparatus; indeed, the entire elastic device 24 could be replaced by asingle elastic band, by a single coil spring, or by other similarelastic apparatus.

Link means 26 are provided to assure that any angular displacements ofthe rocker arms with respect to one another are substantially equal inmagnitude but opposite in direction.

The link means 26 comprise pulley means 50 and 52, and a cable means 54having an adjustable turnbuckle 56. The pulley means 50 and 52 aresecurely attached to rocker arms 18 and 20, respectively, at theirrespective first locations 28 and 34. Cable means 54 is strung as shownin a tight figure 8" pattern about pulleys 50 and 52. With such aconstruction rotation or angular displacement of either pulley or eitherrocker arm will cause movement of cable means 54 which in turn willcause a corresponding equal magnitude but oppositely directed movementof the opposite pulley and rocker arm.

In the embodiment of this invention shown in FIGS. 1 to 3 the elongatedbow member 12 is preferably constructed of a nonfiexible material andcan comprise a plurality of detachable sections 58 and 60 designed, forexample, for telescopic engagement.

FIG. 2 illustrates a side view of the archers bow of FIG. 1. Bolts 68and '70 are shown as one means for rotatably mounting rocker arms 18 and20 together with their respective pulleys 50 and 52 to the elongated bowmember 12.

FIG. 3 is a bottom plan view of the archers bow of FIG. 1 showing thebow in a drawn position. Pulling with one hand upon draw cable means 22has caused rotation or angular displacement of rocker arm members 18 and20. Link means 26 comprising pulleys 50 and 52, as well as cable means54 have assured that the angular displacements of the rocker arms withrespect to one another have been substantially equal in magnitude butopposite in direction. Such displacements have caused the respectivethird locations 32'and 38 of rocker arm members 18 and 20 to move awayfrom each other drawing with them cable means 40 and 44, thereby causingelastic deformation of the elastic band 46 which in turn exerts a forceupon the rocker arm members at their respective third locationsresisting their rotation. That force is exerted along cable means 40 and44.

In the position shown in FIG. 3 the respective first (28 and 34) andthird (32 and 38) locations of rocker arm members 18 and 20, as well asthe line (i.e. cable means 40 and 44) along which the aforementionedforce is applied all lie substantially along a single straight line.Second locations 30 and 36 however are located at substantially equaldistances away from that line. As the torque generated by theaforementioned force acting upon the rocker arms in a manner which wouldcause them to return to their original position is almost zero at theposition shown in FIG. 3, only a very slight force is required to beexerted upon draw cable means 22 to maintain the bow drawn. This is soeven though a great contracting force is being exerted by elastic device24.

FIGS. 4 and 5 illustrate a second embodiment 100 of the archers bow ofthis invention which utilizes an elastically deformable flexible member102, resembling the more commonly known varieties of archers bows, asthe elongated bow member. This elastically deformable flexible member102 has opposite ends 104 and 106 upon which rocker arm members 108 and110 are rotatably mounted. Rocker arm members 108 and 110 are providedwith first (112 and 114), second (116 and 118), and third (120 and 122)locations respectively. These locations are spaced predetermineddistances from each other. The rocker arms are rotatably mounted orfulcrumed to the bow member 102 at their respective first locations 112and 114. A draw cable means or bowstring 124 provided with a turn buckle126 connects rocker arms 108 and 110 at their respective secondlocations 116 and 118.

The positions of rocker arms 108 and 110 in FIG. 4 have been chosen tosimplify the illustration by reducing to a minimum the number of cablesoverlying one another. It is preferable that an actual embodiment of thebow of FIG. 4 be designed so that in its unloaded rest condition therocker arms are positioned so that second location 116, first location112, first location 114 and second location 118 all lie substantiallyalong the same straight line in the orderjust stated.

An elastic device 128 is connected to rocker arms 108 and 110 at theirrespective third locations 120 and 122 applying to those third locationsa force normally resisting any rotation or angular displacement of therocker arm members. In this embodiment the elastic device 128 comprisesfirst connecting means 130 and 132 linking the third locations 120 and122, respectively, of rocker arm members 108 and 110 to points 150 and152 respectively on bow member 102. Points 150 and 152 are located onbow member 102 several inches from ends 106 and 104, respectively. Inother words, first connecting means 130 links the third location 122 ofrocker arm 110 with point 152 on bow member 102, while first connectingmeans 132 links third location 120 of rocker arm 108 with point 150 onbow member 102. These first connecting means may be cables equipped withturn buckles 134.

Link means 136 have been provided to assure that any angulardisplacements of the rocker arms with respect to one another aresubstantially equal in magnitude and opposite in direction. These linkmeans 136 comprise second connecting means 138 and 140 which link therespective third locations 120 and 122 of rocker arm members 108 and 110to the respective second locations 116 and 118 of the other rocker armmember. In other words, second connecting means 138 links secondlocation 116 of rocker arm 108 with the third location 122 of rocker arm110, while second connecting means 140 links second location 118 ofrocker arm 110 with the third location 120 of rocker arm 108. Guidemeans 142 and 144 comprising eyelets, hook eyes or the like may beprovided to slidably secure the second connecting means to bow member102 at points 146 and 148 approximately midway between the opposite ends104 and 106 of bow member 102. Second connecting means 138 and 140 wouldthen pass through the eyes ofsuch eyelets or hook eyes.

FIG. 5 shows the embodiment of FIG. 4 in a drawn and tensioned position.Draw cable means or bowstring 124 has been drawn back causing rotationor angular displacement of rocker arms 108 and 110. Linking means 136comprising second connecting means 138 and 140, and eyelets 142 and 144,have insured that the rotations of rocker arms 108 and 110 have beensubstantially equal in magnitude and opposite in direction. Rotation ofthe rocker arms has caused their respective third locations 120 and 122to separate from one another, and to draw upon first connecting means130 and 132, respectively. This in turn has caused the arching orbending of bow member 102. A force tending to oppose the rotation orangular displacement of rocker arms 108 and has been applied to theirrespective third locations and 122 along respective first connectingmeans 132 and 130. In the position shown in FIG. 5 the respective first(112 and 114) and third (120 and 122) locations of rocker arms 108 and110, as well as the line (i.e., cable means and 132) along which theaforementioned force is applied all lie substantially along a singlestraight line. In this position the torque which is generated by thetension exerted upon first connecting means 130 and 132, and which tendsto cause rocker arms 108 and 110 to return their original positions isessentially zero. Thus, the bow may be held in this position by exertingan extremely small amount of force upon draw cable means or bowstring124 in spite of the fact that considerable tension is being exerted bybow member 102 along connecting means 130 and 132.

To illustrate the advantages of the bow of FIGS. 4 and 5 over aconventional bow of equal draw weight, the following experimental datais provided. A conventional 30-pound bow was compared with a 30- poundbow of the type illustrated in FIGS. 4 and 5. Each bow was drawn apredetermined distance from its rest position and the force required tohold the bowstring at the new position measured.

The above data shows that applicants bow could be held at full draw byexerting an 8-pound force, while a 30-pound force was required to holdthe conventional bow. Further, it can be seen that when loosed thebowstring of the conventional bow would instantly exert a 130-poundthrust on an arrow, while applicant's bow would exert an 8-pound thrustwhich would soon build to 30 pounds. A lighter and less sturdy arrowcould then be shot, without splintering, from applicants bow than fromthe conventional bow.

FIG. 6 is an incomplete exaggerated front view of parts of the bow androcker arm structure at end 104 of the bow of FIGS. 4 and 5, showing amodification which can improve this type of bow. When the rocker arm 108is rotatably mounted at one side of bow 102, as is shown in FIGS. 4-6,the tension on cable 132 acting on rocker arm 108 at third location 120,can develop a torque on the bolt 154 connecting the rocker arm to bowend 104. This in turn can cause the rocker arm and bow end 104 to twistout of the plane containing bow 102 and drawstring 124. In FIG. 6 theposition which the rocker arm might take as a result'of such twisting isshown by dotted lines. Such twisting can be substantially eliminated byproviding a large loop 156 at the end of cable 132, the loop 156 havingthe end portion of bow 102 passing through it. Such an arrangementdistributes the tension of cable 132 to both faces of rocker arm 108 andtends to keep the rocker arm properly upright.

Many variations in the two embodiments of the archers s bow of thisinvention which have been described are possible. All of the cablemeans, draw string means, and connecting means can be constructed ofmetal cable, wire, rope, string, twine, and other similar materials.Turnbuckles can be provided if desired along the various cables of thesedevices to permit adjustment. The rocker arm members may be constructedin any desired shape, such as for example, triangular or in the form ofangle irons. The rocker arm members may be rotatably mounted to the bowmember in any convenient manner such as by means of an appropriate boltor by use of an appropriate hinge. The flexible bow member may beconstructed of wood, metal, plastic or any other convenient material.The same is true for the nonflexible bow member. The first, second andthird locations on the rocker arms may comprise holes piercing therocker arms or merely projections adapted for securing cables and thelike. Many other modifications of this invention will be obvious tothose skilled in the art.

What I claim is:

1. An archers bow comprising:

an elongated bow member having opposite ends;

a rocker arm member pivotally secured to said bow member at each saidend, each said member having a first, second and third location spacedpredetermined distances from one another, each said member being securedto said ends at its first locations and being so oriented that saidrespective second and third locations each lie on an opposite side ofsaid bow member ends;

a flexible draw cable member secured at its opposite ends to said rockerarm members at their respective second locations;

an elastic device interconnecting said members at their respective thirdlocations; and

link means interconnecting said rocker arm members;

said draw cable member and said elastic device together being of equallengths and serving to maintain said rocker arm members in a position ofrest relative to said bow member whereby lines joining, respectively,said second and third locations are parallel to one another;

said rocker arm members being angularly displaced from their saidposition of rest to a fully bow drawn positions during which alterationof said elastic device serves to apply a force to said rocker armmembers in response to the alteration of said elastic device,

said link means serving to assure that the alteration of said rocker armmembers with respect to one another are equal in magnitude and oppositein direction and said respective first and third locations of eachrocker arm member and a line along which said force is applied, with thebow drawn being substantially along a straight line.

2. A bow as defined in claim I wherein said elongated bow membercomprises an elastically deformable fiexible member.

3. A bow as defined in claim 2 wherein said elastic device comprisesfirst connecting means linking at its opposite ends said third locationof one of said rocker arm members with said bow member near said endthereof opposite said one rocker arm member and further linking at itsopposite ends the other of said rocker arm members at its third locationwith said bow member near said end thereof opposite said other rockerarm member.

4. A bow as defined in claim 3 wherein said link means comprises secondconnecting means linking said second location of said one rocker armmember together with said third location of said other rocker arm memberand further linking said third location of said one rocker arm membertogether with said second location of said other rocker arm member.

5. A bow as defined in claim 4 wherein guide means are pro- 7 vided toslidably secure said second connecting means to said bow member atpoints approximately midway between said opposite ends of said bowmember.

6. A bow as defined in claim 1 wherein said elongated bow member isrigid.

7. A bow as defined in claim 6 wherein said link means comprises apulley rotatively secured to each said rocker arm members at theirrespective first locations, and further comprises a cable cooperatingwith said pulleys.

8. A bow as defined in claim 7 wherein said elongated bow membercomprises a plurality of detachable sections.

1. An archer'' s bow comprising: an elongated bow member having oppositeends; a rocker arm member pivotally secured to said bow member at eachsaid end, each said member having a first, second and third locationspaced predetermined distances from one another, each said member beingsecured to said ends at its first locations and being so oriented thatsaid respective second and third locations each lie on an opposite sideof said bow member ends; a flexible draw cable member secured at itsopposite ends to said rocker arm members at their respective secondlocations; an elastic device interconnecting said members at theirrespective third locations; and link means interconnecting said rockerarm members; said draw cable member and said elastic device togetherbeing of equal lengths and serving to maintain said rocker arm membersin a position of rest relative to said bow member whereby lines joining,respectively, said second and third locations are parallel to oneanother; said rocker arm members being angularly displaced from theirsaid position of rest to a fully bow drawn positions during whichalteration of said elastic device serves to apply a force to said rockerarm members in response to the alteration of said elastic device, saidlink means serving to assure that the alteration of said rocker armmembers with respect to one another are equal in magnitude and oppositein direction and said respective first and third locations of eachrocker arm member and a line along which said force is applied, with thebow drawn being substantially along a straight line.
 2. A bow as definedin claim 1 wherein said elongated bow member comprises an elasticallydeformable flexible member.
 3. A bow as defined in claim 2 wherein saidelastic device comprises first connecting means linking at its oppositeends said third location of one of said rocker arm members with said bowmember near said end thereof opposite said one rocker arm member andfurther linking at its opposite ends the other of said rocker armmembers at its third location with said bow member near said end thereofopposite said other rocker arm member.
 4. A bow as defined in claim 3wherein said link means comprises second connecting means linking saidsecond location of said one rocker arm member together with said thirdlocation of said other rocker arm member and further linking said thirdlocation of said one rocker arm member togEther with said secondlocation of said other rocker arm member.
 5. A bow as defined in claim 4wherein guide means are provided to slidably secure said secondconnecting means to said bow member at points approximately midwaybetween said opposite ends of said bow member.
 6. A bow as defined inclaim 1 wherein said elongated bow member is rigid.
 7. A bow as definedin claim 6 wherein said link means comprises a pulley rotatively securedto each said rocker arm members at their respective first locations, andfurther comprises a cable cooperating with said pulleys.
 8. A bow asdefined in claim 7 wherein said elongated bow member comprises aplurality of detachable sections.